Post on 25-Jun-2018
Naval and Ocean Architect and Marine and Arctic Engineer, M.Sc., Ph.D.
Senior Engineer Laboratory for Floating Structures and Mooring Systems, School of Naval Architecture and Marine Engineering, National Technical University of Athens (NTUA).
Adjunct Assistant Professor, TEI of Athens, tmazarakos@naval.ntua.gr
Presentation by
Dr.- Eng. T. P. Mazarakos
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
FerryBox is an autonomous, low maintenance metrology systemwhich has been developed especially for permanent deploymenton ships, metrology platforms and river measurement points forlong - term in situ monitoring of rivers, estuaries, coastal zonesand open sea.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
The figure shows as an example the scheme of the
German FerryBox system.
The water is pumped from a subsurfaceinlet into the measuring circuit of multipleSensors. A debubbling unit removes airbubbles, which may enter the system duringheavy seas. At the same time coarse sandparticles which may be introduced inshallow harbors and which settle and tendto block the tubes are removed as well.Coupled to the debubbler there is aninternal water loop in which the seawater iscirculated with a constant velocity of about1 m/s. This already decreases the tendencyfor building bacterial slimes on sensors andtube surfaces. A small part of the water isfiltered by a hollow-fibre cross-flow filtermodule for automatic nutrient analysis.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Ferry Box (open system) Ferry Box (closed system)
Pictures of commercial available FerryBoxes
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Operational Standard Sensors
Temperature
Salinity
Oxygen
Turbidity
Sensors that need major improvements
Chlorophyll-a-concentration pH/pCO2 Nutrients-Nitrate Nutrients-other Phytoplankton- Groups Phytoplankton and zooplankton by
morphology
Sensor systems that are “on the horizon”
Algal species by genetic sensors Organic micro-pollutants by genetic sensors
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
North Sea & Atlantic
Baltic Sea
Northern Atlantic
Mediterranean Sea
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Ship type and its primary use will influence where and how easily a Ferrybox can beinstalled and operated.
• All ships tend to be different even ships of the same class supplied to the samecompany.• Ships need to be inspected carefully to find the most appropriate location forequipment.• The category of regulations applied on board varies.• Water inlet must be ahead of outlets for black and grey water from the ship(sewage and other contamination).• Work by the crew or for the ship’s operators may interfere with the Ferryboxinstallation.
Ship types: Cargo ships, car/ passenger ferry, Ro/Ro Ship, Container ship, Merchant ships
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
The source of water used should be as close as possible to the Ferrybox installation.This is to avoid contamination both by heat, fouling of the line and other potentialchanges in water properties. Some sensors like inlet temperature or oxygen can beplaced just after the inlet valve.
Different ships may present different opportunities for obtaining water depending onthe size and design of the ship.
A direct intake with a penetration through the hull may be possible this will requirethe Ferrybox system to have a dedicated pump to drive or pull water through thesystem and then return it through a hull outlet to the sea. If the Ferrybox is above theship’s water line the ship’s drainage system can be used.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Water can also be drawn in from the sea chest. This may be more accessible than asimple hull penetration and the sea chest is designed to reduce air bubbles beingpumped into the ships internal cooling water systems.
Connection to internal ship circuits system is possible and can be made at any timethe expertise available. Suitable designs can avoid the installation of dedicatedwater pumps. A key point is to know the quality of the water.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Pumps
If the system is designed with an independent water take off point differenttypes of pump are available, for example peristaltic or impeller pumps.
Valves
For direct penetrations through a hull or into the sea chest the use of ballvalves at the inlet and outlet are recommended, as these make it possible toclean the parts through the hull when the ship is in dry dock.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
A basic design point which affects where and on what ship a system can beinstalled is if the water circuit is open or closed.
In a closed circuit, water is pumped through the system using a single pump andno free water surface is involved reducing the risk of leaks and flooding. Thesystem is more acceptable to a wider range of ship operators.
In an open system, water is pumped into the ship’s systems such as CO2equilibrator form where it flows into a reservoir tank which then has to emptiedand pumped out of the ship using a second pump. This generates a higher riskof leaks and flooding and may be less acceptable to some shipping companies.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Temperature
In most cases the sensors for temperature and salinity operated without
major problems.
Salinity
The salinity sensor requires a high accuracy and long-term stability, for
instance to discriminate between different water masses which differ only
little in salinity (<0.1).
Turbidity
For optical turbidity measurements the signal is very sensitive to biofouling.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
An ADCP mounted under the keel of the ship is an effective tool to monitorwater and sediment transport through channels/straits.
The instrument is attached to the hull of the ferry 30 cm below the hull itself toprevent problems with air bubbles and interference with the turbulence of theship. This technique measures the current field below the moving ferry.
Bulbous
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Underwater glider
The underwater glider, is an autonomous underwater vehicle. It works buoyancydriven and is extremely energy efficient.
The underwater glider, is a relatively new measurement platform and originallydeveloped as a low-cost, long-endurance device for observing the oceans.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Waverider buoy
Data from the buoy are: wave height, wave length and wave period.
A Waverider buoy follows the movements of the sea surface, and determines thewave height by measuring the vertical acceleration of the buoy. At the heart ofall Waverider buoys is an accelerometer, mounted on a horizontal, stabilisedplatform suspended in a fluid filled sphere in the bottom of the Waverider buoy.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Monopiles
Tripod
Offshore Structures...
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
All marine science has an important practical side in relation to overcoming the
problems of working in the often harsh environment of the sea. Sea worthiness
requires robust systems that work well in harsh physical conditions. Relaying
data to users also requires a robust supply chain. Added to these demands are
the extra ones associated with working with shipping companies and their
commercial constraints and on ships that were not designed as scientific
laboratories.
*Laboratory for Floating Structures and Mooring Systems, School of Naval Architecture and Marine Engineering, National Technical University of Athens, Greece
tmazarakos@naval.ntua.gr#Hellenic Centre for Marine Research, Director, Anavissos, Greece
mavrakos@naval.ntua.gr
Presentation by
Dr.- Eng. T. P. Mazarakos
T.P. Mazarakos* and S. A. Mavrakos*#
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Aristeia4: Ν35.43°, Ε26.80°
(200m)
Rocky - semi-rocky soil
formations
Aristeia6: Ν40.05°, Ε25.20°
(120m)
No rock formations soil
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Top view of floating structure and
basic characteristics of its parts.
Side view of floating structure and basic
characteristics of its parts.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Floating Platform Geometry
Geometrical Dimensions of each OWC deviceRadius of inner concentric cylindrical body
5m
Draft of inner concentric cylindrical body
20m
Outer & inner radius of the oscillating chamber in each device
14-14.5m
Oscillating chamber’s draft 8mSpacing between offset columns 50mLength of Main column (tower base)
20m
Diameter of pontoons and cross braces
1.6m
Draft 20mElevation of main column (tower base above SWL)
10m
Mass
Characteristics
Platform Mass (including ballast) 2.1836x106kg
Displacement 6086.3t
KG (below SWL) 4.05m
Platform roll inertia 1.5x109kgm2
Platform pitch inertia 1.5x109kgm2
Platform yaw inertia 2.7x109kgm2
Mooring SystemNumber of mooring lines 3
Mooring line diameter 130mm
Mooring line Mass per unit length 104kg/m
Mooring line mass in water 888.6N/m
Young's modulus of elasticity (E) 200GPa
Equivalent mooring line extensional
stiffness (EA)
2646MN
Total Restoring coefficient Kxx (depth
200m)
180KN/m
Total Restoring coefficient Kzz (depth
200m)
44.1MN/m
Pretension 32.4MN
WT masses and center of mass
WT components Mass [t] Zcg [m] Length [m]
Tower 250 43.3 77.6 (+10)
Nacelle 240 89.45 -
Hub 50 90 -
Blade x 3 17.74 ~90 61.5 (+1.5)
Wind Turbine Geometry
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Analytical Method (Computer Code: HAMVAB- S. A. Mavrakos, 1995)
Reduce Order Model of the WT (Mavrakos, 2015, Mazarakos, 2015)
Coupled Analysis- RAO’s (Computer Code: HYDRAEROFLOAT-
T. P. Mazarakos, 2015)( ) ( )
( )
ij
ij
WT WTM A M x B B xij ij ij
i tWTC C C x F emooringsij
(Floater mass)
Tower
Nacelle - Hub
Blade x 3
Hydrodynamic Calculations for the Floating Platform POSEIDON
(120m)
Exciting Wave Forces
Motions
Air Pressure
Volume Flow
Drift Forces
Added Mass/ Damping
Wave Drift Damping
Shear Forces
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece
Surge motion of the TLP combined floating platform, 3
OWC’s and wind turbine system. Wave heading 0
degrees.
7th FerryBox Workshop,7-8 April Heraklion Crete, Greece